Drupal is an open source content management framework; which means no vendor lock-ins and no expensive licensing. It also means that codebase is available free for all and can be used to build applications and website CMS. Drupal is supported by a passionate community of thousands of PHP developers who collectively work on improving the functionality, security and enterprise level features that this framework offers. As a business owner, you would like to never want to be stuck if a non-responsive or out-of-business web developer. You can hire any other developer and they can start development without having to go through the code or understand nuances.